1. Field of the Invention
The present invention generally relates to a power transmission element incorporating a drive connection between a rotatable wheel and a flexible drive or driven member in the form of a rope in which the periphery of the wheel includes a pair of divergent surfaces and a groove having a plurality of circumferentially spaced and arranged impressions therein which are radially and circumferentially curved with the tapering portions of the impressions extending along the circumference of the wheel rather than radially thereof to provide a drive connection between the wheel and rope.
2. Description of the Prior Art
Transmission of power by using a flexible power transmitting element engaged with a pulley rotatable about an axle has been used for many years and has included pulleys with flat surfaces for engaging flat drive belts, pulleys with a V-shaped groove for engaging V belts and similar types of structures in which friction between the pulley and flexible element serves to transmit power and to perform work. Various efforts have been made to modify rope pulleys to increase the frictional engagement between the rope and pulley but such devices usually employ radial converging surfaces, such as ribs or lugs, on the radially converging surfaces of the pulley groove which increase friction but even so, slippage will occur between the rope and pulley when a sufficient load is encountered when the compressed diameter of the rope or cable is insertable in the narrowest construction of the walls of the pulley or sheave. The following U.S. patents are typical of the developments in this type of drive systems:
1,231,856; July 3, 1917
1,458,425; June 12, 1923
2,875,981; March 3, 1959
3,302,932; February 7, 1967
3,714,838; February 6, 1973